7 Words in my understand that help me cognitively internalize God as Trinity: 

Mystery: He is a Being beyond comprehensive understanding. 

Uncreated: God exists continually outside the created order; self-existent.

Three: God is three persons or three with own identifying personhoods. 

Same:  God is same in essence, substance, character, nature and manifested in glory.

Complete: God is in every way perfect and relates out of love not need. 

Fellowship: Conditionally-oriented bond based in unchanging-faithful interdependent love.